Conventionally, whether timing characteristics of a circuit-under-design conform to a standardized value is determined by a simulation based on a resistance value and a capacitance value from wiring information after layout design. The timing characteristics are characteristics of set-up timing and hold timing, for example. A technique has been known that changes the size of a cell in the circuit-under-design to make the timing characteristics and the power consumption value characteristics of the circuit-under-design conform to standardized values (hereinafter, “conventional technology 1”) (see, e.g., Japanese Patent Laid-Open Publication Nos. 2004-5578 and H9-107035). A technique has been known that performs design such that a power consumption value conforms to a standardized value in a circuit-under-design having the timing characteristics conforming to a standardized value (hereinafter, “conventional technology 2”) (see, e.g., Japanese Patent Laid-Open Publication No. 2002-342400).
Variations occur in the characteristics of cells of a circuit-under-design and the characteristics of the circuit-under-design due to factors at manufacture. Therefore, a technique has been known that calculates the characteristics distribution of the cells and the characteristics distribution of the circuit-under-design with a polynomial equation (see, e.g., Japanese Patent Laid-Open Publication No. 2007-133497). A technique has also been known that performs a simulation with consideration of the variations (see, e.g., Japanese Patent Laid-Open Publication Nos. H9-265488 and 2005-19524).
However, cell size is changed while a layout is being designed in conventional technology 1. The process is executed after the layout design in conventional technology 2. For example, since the layout design is performed again if a change is made in a circuit-under-design, it is problematic that the layout design requires considerable effort, which makes design difficult. The technique of performing a simulation with consideration of the variations is unable to perform the design with consideration for variations of characteristics. Therefore, since multiple types of characteristics are not necessarily related, it is difficult to make multiple types of characteristics conform to the standardized values of the respective characteristics.